Download Finding Hot-Jupiters by Gaia photometry using the Directed Follow

Finding Hot-Jupiters by
Gaia photometry using the
Directed Follow-Up strategy
Yifat Dzigan
Postdoctoral Fellow
Weizmann institute of Science
- March 24, 2014
Transiting Exoplanets (especially Hot-Jupiters):
what can they tell us?
1.  Radius of the planet
2.  Orbital inclination and Mass when combined with
radial velocity
3.  Spin-Orbit (Mis)alignment angle
4.  Albedo (reflected light)
5.  Atmospheric spectral features
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Transiting Exoplanets:
The challenge
In order to detect 1 typical HJ we have to observe thousands of stars
with full coverage
Transit detection is a bit like playing the slot machine:
⚂  Observe many stars
⚂  Frequent observations
 Dedicated surveys (COROT)
 High-cadence
 Dense fields
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Deleuil et al. (2008)
ASTROPHYSICS
Transiting Exoplanets:
Low-cadence surveys
planetary transits from Hipparcos photometry!
Arenou
e de Paris, CNRS UMR 8633, 92195 Meudon CEDEX, France ([email protected]; [email protected])
Hipparcos Epoch photometry - HD209458
s 39-month mission, Hipparcos observed
n 89 occasions. Five of these observations
ond to epochs of planetary transits, with a
ease of flux in the Hp band being observed
s a result of the long temporal baseline of
etween the Hipparcos and radial velocity
curate orbital period of P = 3.524739 ±
e derived from the Hipparcos photometric
planetary systems – stars: individual:
of the photometric detection of the plane209458 by Charbonneau et al. (1999) and
epresents a significant confirmation of the
r planets detected by radial velocity meafies the start of a new era for extrasolar
7.70
7.72
HIPPARCOS magnitude HP
1999 / Accepted 7 December 1999
7.74
7.76
7.78
7.80
7.82
7800
8000
8200
8400
8600
8800
Observation date (JD-2,440,000)
9000
Robichon & Arenou (2000)
Fig. 1. Hipparcos individual photometric observations of HD 209458
as a function of the observation epoch (given in barycentric Julian
Date).
“Hipparcos Catalog does not represent a likely place to detect planets in the absence
(Jenkins et al. 2002)
orbital period (≈ 3.5 days), the transit dura- of
2. other
Hipparcosinformation”
photometric measurements
liesGaia
a 3%and
probability
of observing a transit
the Unseen
The Hipparcos Epoch Photometric data are part of the published
n average,
about
a
hundred
individual magThe Brown Dwarf Question
- MarchHipparcos
24, 2014Catalogue (ESA, 1997). It is available on CD-ROM,
per star were obtained by Hipparcos dur-
Directed Follow-Up (DFU) strategy
for low-cadence surveys
Sampled transits provide some information about the
hypothetical transit, if it exists.
Using MCMC we can present this scarce information as
a Probability Distribution Function
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Directed Follow-Up strategy
for low-cadence surveys
Low-cadence
observations
MCMC: posterior
distributions
Instantaneous Transit
Probability – ITP(t)
Prioritize stars for
follow-up observations
Perform follow-up
observations
Planetary candidate
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
DFU Application to Hipparcos Epoch
Photometry – HD 209458
lanetary transits from Hipparcos photometry!
enou
Paris, CNRS UMR 8633, 92195 Meudon CEDEX, France ([email protected]; [email protected])
9-month mission, Hipparcos observed
9 occasions. Five of these observations
d to epochs of planetary transits, with a
e of flux in the Hp band being observed
result of the long temporal baseline of
een the Hipparcos and radial velocity
ate orbital period of P = 3.524739 ±
erived from the Hipparcos photometric
anetary systems – stars: individual:
he photometric detection of the plane458 by Charbonneau et al. (1999) and
esents a significant confirmation of the
lanets detected by radial velocity meas the start of a new era for extrasolar
Low-cadence Hipparcos observations
7.70
7.72
HIPPARCOS magnitude HP
9 / Accepted 7 December 1999
7.74
7.76
7.78
7.80
7.82
7800
8000
8200
8400
8600
8800
Observation date (JD-2,440,000)
9000
Fig. 1. Hipparcos individual photometric observations of HD 209458
as a function of the observation epoch (given in barycentric Julian
Date).
Gaia and the Unseen
Brown
- March2.24,
2014 photometric measurements
talThe
period
(≈ 3.5Dwarf
days),Question
the transit duraHipparcos
Robichon & Arenou (2000)
DFU Application to Hipparcos Epoch
Photometry – HD 209458
MCMC – posterior distributions
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Dzigan & Zucker (2011)
HD 209458: Follow-Up predictions
Instantaneous Transit Probability –ITP(t)
r
Best times fo
Follow-Up
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Dzigan & Zucker (2011)
HD 209458: Hipparcos combined with
a Directed Follow-Up simulation
Posterior Distributions
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
ITP (t)
Dzigan & Zucker (2011)
ITP degradation
probability
ITP for 10 years after Hipparcos observed HD 209458
t – 244000 (JD)
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
t – 244000 (JD)
Dzigan & Zucker (2011)
Transiting Exoplanets
by Gaia photometry
Photometry <2 mmag
down to the 15th
G - magnitude
Average of 70 samples
per object
de Bruijne, J. H. J. (2012)
Optimized to derive parallaxes, proper motions,
not for planetary transit search!
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Is it worth it?
Gaia yield of transiting planets
2
d
f ( R p , p)
d 6 N det
dn
2
= ρ∗ (r , l , b)r cos b
Pdet ( M , r , R p , p)
dR p dpdMdrdldb
dM dR p dp
(Beatty & Gaudi 2008)
"  
Transiting HJs & VHJs frequencies from OGLE complete survey
(Gould et al. 2006)
"  
Stellar density in the solar neighborhood (Reid et al. 2002)
"  
Galactic model (Bahcall & Soneira 1980)
"  
Transit detection probability as an Observational Window Function
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Gaia Transit Observational
Window Function
Assumptions:
Gaussian noise
No outliers
Minimum number of
points in transit (3,5,7)
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Dzigan & Zucker (2012)
Gaia expected yield
Assuming 2-hours transit…
"  
Down to 14th G-magnitude:
minimum 7 transits: ~70 transiting HJs and VHJs
minimum 5 transits: ~200
minimum 3 transits: ~600
"  
Down to 16th G-magnitude:
minimum 7 transits: ~300 transiting HJs and VHJs
minimum 5 transits: ~900
minimum 3 transits: ~2600 Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Directed Follow-Up strategy
application for Gaia
CU-7 for Variability Processing
Laurent Eyer
University of Geneva
Department of Astronomy
"  
Simulated Gaia light curves inspired by known transiting planets
(period, duration, coordinates)
"  
Gaia Scanning Law
"  
Phase chosen to produce required number of sampled transits
"  
Photon noise level – 1 mmag.
"  
We defined two main detection scenarios.
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
First scenario - Gaia data alone
•  Simulation inspired by CoRoT-1b (P=1.51 d, w=0.1 d)
•  Assuming five sampled transits (Ntot=64)
•  d > 0.005 mag
Period Posterior distribution
ITP
d=10 mmag
d=8 mmag
d=5 mmag
P (days)
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
t (days)
Dzigan & Zucker (2013)
Second scenario – DFU observations
with as little as 3 transit samples we will be able to trigger follow-up
•  Simulation inspired by WASP-4b (P=1.338 d, w=0.104 d)
•  Assuming four sampled transits (Ntot=83)
•  d = 0.005 mag
Gaia simulation
Period Posterior distribution
ITP
Gaia combined with 1 DFU simulation
Gaia combined with 2 DFU simulations
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Dzigan & Zucker (2013)
Prioritizing candidates for
Directed Follow-Up observations
1. ITP peak values > 0.1
3. Wald statistic of the transit depth
2. Skewness of the ITP >1
ITP
probability
Transit
simulation
t (days)
No Transit
t (days)
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
False alarm treatment
"   Statistical false-alarm rate is negligible
"   Red noise will manifest as effectively white noise
probability
ITP for simulation with no transit (σ=3 mmag)
t (days)
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Initiating the Follow-Up campaign
probability
ITP degradation
t (days)
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
As soon as possible…
(while Gaia still operates)
Directed Follow-Up for Gaia
Partial light-curve
WASP-12b: 3 transit samples @ half lifetime, d=7 mmag
Gaia halftime simulation
Gaia halftime + 1 DFU simulation
Gaia halftime + 2 DFU simulations
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Follow-Up network for
Gaia discoveries
"   Widespread
"   Moderate precision
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Summary & Future
"   Transiting Hot Jupiters are valuable (favorable for
observational study)
"   The Directed Follow-Up strategy utilizes low-cadence
surveys for transit search
"   Gaia yield can reach thousands of transiting planets
"   More applications in many astrophysical phenomena
(Eclipsing Binaries… ) and surveys (OGLE, LSST…)
Thank you
Gaia and the Unseen
The Brown Dwarf Question - March 24, 2014
Dzigan & Zucker, 2011, MNRAS
Dzigan & Zucker, 2012, ApJL
Dzigan & Zucker, 2013, MNRAS